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1 March 2019 Novel direct conversion imaging detector without selenium or semiconductor conversion layer
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It has been reported and discussed that electrical current can be produced when an insulating material interacts with ionizing radiation. We have found that high-resolution images can be obtained from insulating materials if this current is guided by an electric field to the pixels of a TFT array. The charge production efficiency of insulators is much smaller than that of photoconductor materials such as selenium, silicon, or other conventional semiconductors. Nevertheless, when the intensity of the ionizing radiation is sufficiently high, a charge sensitive TFT imaging array with only dielectric material can produce high MTF images with contrast resolution proportional to the intensity of the radiation. The function of the dielectric in this new detector may be similar to that of an ionization chamber. Without the semiconductor charge generating material, the dielectric imaging detector does not exhibit charge generation fatigue or charge generation saturation. Prototype detectors have been tested using diagnostic x-ray beams with energy ranging from 25 kVp to 150 kVp, and therapeutic 2.5MV, 6MV, 10MV, and 15MV photon beams (with and without an electron built-up layer), electron beams, broad area proton beams, and proton pencil beams in the energy range of 150 MeV. High spatial resolution images up to the Nyquist frequency have been demonstrated. The physics, structure, and the imaging properties as well as the potential application of this detector will be presented and discussed.
Conference Presentation
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Denny L. Lee, Andrew Maidment, Ali Kassaee, Lei Dong, Taoran Li, Trevor Vent, Heather Petroccia, Peyton Irmen, Irina Malajovich, Kang Heo, Dooho Kim, and Hyunsuk Jang "Novel direct conversion imaging detector without selenium or semiconductor conversion layer", Proc. SPIE 10948, Medical Imaging 2019: Physics of Medical Imaging, 1094818 (1 March 2019);

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